Exam Complete

CBC BASICS

• What is Hematology?
    - The study of blood and blood disorders.
    - Definition: "What is hematology? the study of blood and blood disorders."

• What is a CBC?
    - Complete Blood Count.
    - Includes the following components:
      - RBC (Red Blood Cells)
      - WBC (White Blood Cells)
      - PLT (Platelets)
      - HGB (Hemoglobin)
      - HCT (Hematocrit)
      - RBC indices
      - Differential
    - Common Tests: CBC/D, ESR, INR, PT, APTT, D-dimer.
       - Verbatim: "Common tests: CBC/D (everyone), ESR, INR, PT, APTT, D-dimer."

• Tube Colours
    - Lavender (EDTA)
      - Used for CBC/D.
      - Stable for 8 hours.
    - Blue top (sodium citrate)
      - Used for coagulation tests, has a 1:9 ratio.
      - Draw first unless cultures are required.
    - PT/INR
      - Stored at room temperature (factor V is labile).
    - APTT
      - Must be performed within 4 hours (2 hours if on heparin).

NORMAL RANGES (MEMORIZE)

• WBC Normal Range: 4.0–11.0 ×10⁹/L
    - Increased levels indicate bacterial infection or leukemia.
    - Decreased levels indicate viral infection.

• RBC Normal Ranges:
    - Male: 4.7–6.1 ×10¹²/L
    - Female: 4.2–5.4 ×10¹²/L

• Hemoglobin Levels:
    - Male: 140–180 g/L
    - Female: 120–160 g/L

• Hematocrit (HCT):
    - Male: 0.42–0.52
    - Female: 0.37–0.47

• Rule of 3:
    - Formula: RBC × 3 = HGB
    - Formula: HGB × 3 = HCT ± 3
    - Definition: "Known as 'rule of 3' RBC x 3 = HgB; HgB x 3 = Hct + 3."

• MCV (Mean Corpuscular Volume):
    - Normal Range: 80–100 fL
    - <80 indicates microcytic cells; >100 indicates macrocytic cells.
    - Formula: $ext{MCV} = rac{ ext{HCT}}{ ext{RBC}} imes 1000$

• MCH (Mean Corpuscular Hemoglobin):
    - Normal Range: 27–31 pg
    - Formula: $ext{MCH} = rac{ ext{HGB}}{ ext{RBC}}$

• MCHC (Mean Corpuscular Hemoglobin Concentration):
    - Normal Range: 320–360 g/L
    - Critical: >360 (indicative of spherocytosis, hemolysis, burns).
    - False increase due to cold agglutinins.

• Platelets (PLT):
    - Normal Range: 150–450 ×10⁹/L
    - Critical Values: <20 or >1000 ×10⁹/L

• RDW (Red Cell Distribution Width):
    - Normal Range: 11.5–14.5%
    - High RDW is indicative of anisocytosis and is the first indication of anemia.

WBC DIFFERENTIAL

• Relative % of WBC Types:
    - Neutrophils: 40–70%
    - Lymphocytes: 20–40%
    - Monocytes: 2–8%
    - Eosinophils: 1–4%
    - Basophils: 0.5–1%

• Absolute Count Formula:
    - Absolute = WBC × (%/100)
    - Explanation: "Absolute count does this by: (each WBC %) x (PT total WBC count)."

RBC MORPHOLOGY

• Normal RBC Characteristics:
    - Size: 7–8 µm
    - Shape: Biconcave disc
    - Central pallor accounts for 1/3 of diameter.

• Key Abnormal Shapes:
    - Spherocytes: No central pallor, elevated MCHC.
    - Target cells: Associated with liver disease and thalassemia.
    - Schistocytes: Related to DIC, TTP, HUS.
    - Teardrop cells: Associated with myelofibrosis and thalassemia.
    - Ovalocytes/Elliptocytes: Seen in hereditary elliptocytosis and megaloblastic anemia.
    - Sickle cells: Contain HbS.
    - Acanthocytes: Associated with liver disease and abetalipoproteinemia.
    - Echinocytes (burr cells): Indicate renal disease or may be an artifact of drying.

• Colour Changes:
    - Hypochromia: Includes large central pallor.
    - Hyperchromia: MCHC >360 (indicative of spherocytes).
    - Polychromasia: Indicates reticulocytosis.

• Inclusions:
    - Howell-Jolly bodies: Remnants of DNA, typically seen post-splenectomy.
    - Basophilic stippling: Associated with lead poisoning and thalassemia.
    - Pappenheimer bodies: Contain iron granules.
    - Heinz bodies: Indicate G6PD deficiency (seen with supravital stain only).
    - Cabot rings: Seen in megaloblastic anemia.
    - HbC crystals: Bar-shaped formations.
    - HbSC crystals: Recognized as “glove-like.”

WBC MORPHOLOGY

• Toxic Changes:
    - Toxic granulation: Sign of bacterial infection.
    - Döhle bodies: Associated with infection, burns, and pregnancy.
    - Toxic vacuolization: Sign of sepsis.

• Left Shift:
    - Indicates an increase in bands, metas, and myeloblasts, typically signifying infection.
    - Explanation: "A shift to the left… increase in immature neutrophil precursors."

• Hypersegmentation:
    - Presence of 6 lobes: Indicative of megaloblastic anemia.

• Hyposegmentation:
    - Example: Pelger-Huët anomaly.

PLATELET MORPHOLOGY

• Normal Platelet Characteristics:
    - Size: 1–4 µm

• Giant Platelets:
    - Indicative of increased turnover (conditions such as ITP and post-splenectomy).

HEMATOPOIESIS

• Sites of Hematopoiesis:
    - Fetus: Primarily occurs in the liver and spleen.
    - Adult: Mainly occurs in the bone marrow.
    - Extramedullary (pathologic): Occurs in the liver and spleen, potentially leading to hepatosplenomegaly.
    - Explanation: "Extramedullary… can lead to organ strain, which results in hepatosplenomegaly."

• Stem Cells:
    - Description: Pluripotent stem cells differentiate via various cytokines (EPO, G-CSF, GM-CSF).

• M:E Ratio:
    - Normal Ratio: 2:1 to 4:1
    - Increased M:E: May indicate infection or chronic myelogenous leukemias (CML).
    - Decreased M:E: Seen in erythroid hyperplasia and hemolysis.
    - Explanation: "Normal ratio is 2:1 to 4:1."

SPLEEN FUNCTIONS

• Functions:
    - Filters RBCs from the circulation.
    - Stores 1/3 of platelets and granulocytes.
    - Immune function, particularly in supplying opsonizing antibodies.
    - Explanation: "Spleen supplies opsonizing antibodies… strips the capsule."

• Post-Splenectomy Smear:
    - Indicative findings include Howell-Jolly bodies, target cells, and thrombocytosis.

BLOOD SMEAR PREPARATION

• Good Smear Requirements:
    - Cover 2/3 of the slide.
    - Form a feathered edge.
    - No visible streaks, ridges, or clumps.
    - Explanation: "Good smear has: smooth gradient… feathered edge."

• Artifacts:
    - Burr cells: Result from a drying artifact.
    - Refractile RBCs: Indicate water contamination.
    - Presence of WBCs in the tail: Indicates the smear was too thin.

• Platelet Estimate:
    - Calculation: Average number of platelets in 10 fields × 20.

• WBC Estimate:
    - Calculation: Average number of WBCs in 10 fields × 2.

STAINS (WRIGHT–GIEMSA)

• Dyes Used:
    - Eosin Y: Provides pink color to the cytoplasm.
    - Methylene blue: Stains nuclei blue.
    - Explanation: "Anionic dye (eosin Y)… methylene blue… staining nucleus."

• pH Effects:
    - Too acidic conditions yield bright red RBCs.
    - Too alkaline conditions produce blue-green RBCs.

ESR (ERYTHROCYTE SEDIMENTATION RATE)

• Principle:
    - Based on rouleaux formation, which leads to faster settling of red cells.
    - Explanation: "Based on Stoke’s law… affected by plasma protein concentration."

• Increased ESR Causes:
    - Indicative of inflammation, infection, pregnancy, cancer, and autoimmune diseases.

• Decreased ESR Causes:
    - Seen in sickle cells, spherocytes, and polycythemia.

• Normal Values:
    - Men: 0–15 mm/hr
    - Women: 0–20 mm/hr

BONE MARROW

• Indications:
    - Evaluated for unexplained cytopenias, staging of leukemia and lymphoma, and for storage diseases.

• Sites for Sampling:
    - Commonly from the posterior iliac crest.

• Aspirate vs Biopsy:
    - Aspirate: Provides information about morphology.
    - Biopsy: Offers insight into architecture and cellularity.

• Cellularity Estimate:
    - Formula: ext{Cellularity} ext{ estimate} = 100 - ext{ age} ext{ ± } 10 ext{%}

RBC INDICES (FORMULAS)

• Formulas:
    - $ext{MCV} = rac{ ext{HCT}}{ ext{RBC}} imes 1000$
    - $ext{MCH} = rac{ ext{HGB}}{ ext{RBC}}$
    - $ext{MCHC} = rac{ ext{HGB}}{ ext{HCT}}$
    - $ext{RDW} = ext{size variation}$

ANEMIA CLASSIFICATION

• Microcytic/Hypochromic Anemias:
    - Examples: Iron deficiency anemia, thalassemia, sideroblastic anemia.

• Macrocytic Anemias:
    - Causes: B12/folate deficiency (characterized by oval macrocytes and hypersegmented neutrophils), alcoholism (produces round macrocytes).

• Normocytic Anemias:
    - Causes: Acute blood loss, hemolysis, chronic disease.

HEMOLYSIS

• Extravascular Hemolysis: Accounts for approximately 90% of hemolysis, occurs in the spleen and liver leading to elevated bilirubin and spherocytes.

• Intravascular Hemolysis: Accounts for approximately 10% of hemolysis, involves free HGB leading to decreased haptoglobin, hemoglobinuria, and hemoglobinemia.

BODY FLUIDS

• CSF (Cerebrospinal Fluid):
    - Tube 1: Chemistry
    - Tube 2: Microbiology
    - Tube 3: Cell Count
    - Tube 4: Extra Tests
    - Normal WBC count: ≤5 ×10⁶/L.

• Serous Fluids: Differentiate between transudate and exudate based on protein content, WBC count, and appearance.

• Synovial Fluid: Crystals observed in gout (uric acid) and pseudogout (CPPD).

AUTOMATION

• Principles of Blood Analysis:
    - Electrical impedance
    - Hydrodynamic focusing
    - Scatterplots
    - Flow cytometry
    - Spectrophotometry: Used for hemoglobin measurement.

RETICULOCYTES

• Normal Range: 0.5–2% of total RBCs.
    - Increased levels indicate hemolysis or blood loss.
    - Visualized as polychromatic cells.

CRITICAL VALUES

• WBC Critical Values: <3 or >25 ×10⁹/L

• HGB Critical Values: <70 or >190 g/L

• PLT Critical Values: <20 or >1000 ×10⁹/L

BLOOD COMPONENTS

• Blood Composition:
    - Total: 4–6 L
    - Represents approximately 8% of body weight.
    - pH Range: 7.35–7.45
    - Plasma: 55% of blood
    - Formed elements: 45% of blood, consisting of:
      - RBC: 44%
      - WBC + PLT: 1%

• Plasma Composition:
    - 91.5% water
    - 8.5% solutes, including:
      - Albumin (55%)
      - Globulins (38%)
      - Fibrinogen (7%)

MORPHOLOGY TABLES (FULL DETAIL)

• RBCs:
    - Evaluated in areas where cells do not overlap.
    - Size: 7–8 µm
    - Mean volume: 90 fL
    - Anucleate.
    - Shape: Biconcave disc with central pallor.
    - Uniform size and shape.

• Platelets:
    - Size: 1–4 µm
    - Count: 7–15 per oil field.
    - Cytoplasm: Bluish with reddish-purple granules.
    - Function: Adhesion, aggregation, and coagulation surface function.

• Segmented Neutrophils:
    - Size: 14–16 µm
    - Structure: 3–4 lobes with coarse chromatin.
    - Cytoplasm: Light pink and granular (50–70% in adults).

• Band Neutrophils:
    - Structure: C/S-shaped nucleus with clumped chromatin.
    - Cytoplasm: Pink with secondary granules.

• Eosinophils:
    - Properties: Slightly larger than neutrophils, bilobed nucleus, orange-red granules.
    - Typical Count: 0–4%, which increases at night.

• Basophils:
    - Size: Large, with purple-black granules and light blue cytoplasm.
    - Typical Count: 0–2%; granules are water-soluble.
    - Count may increase at night.

• Lymphocytes:
    - Size: 7–10 µm
    - N:C ratio: 4:1 to 2:1; clumped chromatin with clear blue cytoplasm.
    - Count: 20–44%; large lymphocytes may be indented by RBCs.

• Monocytes:
    - N:C ratio: 1:1 to 2:1; kidney-bean shaped nucleus with lacy chromatin.
    - Cytoplasm: Ground-glass appearance.
    - Count: 2–9%, may have pseudopods.

HEMATOPOIESIS OVERVIEW

• Definition: Production, development, differentiation, and maturation of all blood cells.

• Daily Production Rates:
    - RBC: 3 billion
    - WBC: 1.5 billion
    - Platelets: 2.5 billion

• Stem Cells:
    - Nature: Pluripotent
    - Regulation: Controlled by cytokines (EPO, G-CSF, GM-CSF, interleukins).

• Sites: Bone marrow, liver, spleen, lymph nodes, and thymus.

• Extramedullary Hematopoiesis:
    - Occurs in the spleen and liver when the bone marrow cannot meet demand, leading to hepatosplenomegaly.

SPLEEN FUNCTIONS

• Functions of the Spleen:
    - RBC filtration
    - Storage of WBCs and platelets
    - Immune function with opsonizing antibodies for encapsulated bacteria.
    - Storage of 1/3 of platelets and 1/3 of granulocytes.

• Post-Splenectomy Smear:
    - Common findings include Howell-Jolly bodies, target cells, and thrombocytosis.

BONE MARROW & M:E RATIO

• M:E Ratio:
    - Normal: 2:1 to 4:1
    - Increased M:E: Indicates infection, CML, and erythroid hypoplasia.
    - Decreased M:E: Signals erythroid hyperplasia, hemolysis, polycythemia vera (PV), megaloblastic anemia, and myeloid hypoplasia.

• Erythropoietin (EPO):
    - Produced by the kidneys in response to hypoxia.
    - Promotes faster maturation of RBCs from 5 days to 3–4 days.